1. Field of the Invention
The invention relates to a fan system, and in particular to a fan system capable of enhancing the output power and reducing the cost.
2. Description of the Related Art
Electronic systems generate heat based on the amount of data they process. Because some electronic systems provide fast and continuous operations, heat dissipation devices for these electronic systems are more important. Various heat dissipation products are provided, and fan systems are currently among the popular.
FIG. 1 depicts a conventional fan system. A fan system 1 is electrically connected to a power supply 2 to receive the power. The fan system 1 comprises a drive device 10, a sensor 20, a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a coil L. The drive device 10 is electrically connected to the power supply 2. The sensor 20 can be a Hall sensor and is electrically connected to the drive device 10. The first switch S1, the second switch S2, the third switch S3, the fourth switch S4, and the coil L that constitute a bridge connection. The first switch S1 and the second switch S2 is electrically connected to the power supply 2 and the drive device 10, respectively. The third switch S3 and the fourth switch S4 are electrically connected to the drive device 10, respectively.
The drive device 10 controls the switches S1 to S4 to turn on or off so that current flowing through the coil L is changed, and thus a motor (not shown in FIG. 1) disposed in the fan system 1 and having the coil L is driven. The sensor 20 is used to detect the rotation rate of the motor and generate a signal to the drive device 10. Therefore, the drive device 10 adjusts the rotation rate of the motor according to the signal.
FIG. 2 depicts another conventional fan system. A fan system 3 is electrically connected to a power supply 2 to receive the power. The fan system 3 comprises a drive device 30, a sensor 20, and a coil L. The drive device 30 is electrically connected to the power supply 2. The sensor 20 can be a Hall sensor electrically connected to the drive device 30. The coil L is electrically connected to the drive device 30. The difference between the fan systems 1 and 3 is that the drive device 30 is implemented by an integrated circuit (IC) to dispose the first to fourth switches S1 to S4 in the drive device 30. The first to fourth switches S1 to S4 and the coil L form a bridge connection.
Most elements of the fan system 3 are the same as those of the fan system, and description of the fan operation is omitted.
In FIG. 1, the fan system 1 disposes the switches S1 to S4 outside of the drive device 10. Thus, the circuit of the fan system 2 is complicated that has a large number of elements. Thus, it requires more working time, manpower, and cost in test or production process. Therefore, the fan system 3 is developed to replace the fan system 2. In the fan system, the switches disposed in the drive device 30 so that generates heat easily. The drive device 30 thus operates at a high temperature and easy to damage. Moreover, the configuration of the fan system 3 causes low output power, and the suitability and economic benefits of the fan system 3 is less than the fan system 1.
The two described fan systems both have some drawbacks. Thus, an improved fan system is desired to provide.